The invention relates to a two-stroke internal combustion engine with at least one cylinder opening into an exhaust passage with a diffuser-type flare established by the shape of the lower contour.
In the design of two-stroke engines the configuration of the exhaust passage is optimised with regard to the flow pattern arising when the exhaust port is completely open. To promote the exchange of charge, large flow cross-sections are desirable. There are, however, design limits to the size of the exhaust cross-section. In particular, the maximum admissible dimensions of the window forming the transition from the exhaust passage into the cylinder will put a limit on the size of the flow cross-section, since neither height nor width of the window can be increased at will.